Effect of Nb content on the microstructure and corrosion resistance of FeCoCrNiNbx high-entropy alloys in chloride ion environment

In this paper, FeCoCrNiNb x high-entropy alloys were prepared by vacuum arc melting, and their microstructure and corrosion resistance in a chloride ion environment were investigated. The results indicated that FeCoCrNi alloy was a single FCC solid solution and FeCoCrNiNb x alloy was a duplex alloy with FCC phase and Laves phase. FeCoCrNiNb 0.15 showed the best corrosion resistance. The corrosion current density of FeCoCrNiNb 0.15 decreased by one order compared with 316LSS, and the corrosion rate after the immersion experiment was only one-third of 316LSS. The P-N junction improved the corrosion resistance of the passive film of FeCoCrNiNb 0.15 , while the passive film of FeCoCrNi mainly exhibited n-type semiconductor characteristics with less obvious p-type semiconductor characteristics. In this study, FeCoCrNiNb x (x = 0, 0.15, 0.33, 0.5) high-entropy alloys were prepared by vacuum arc melting. FeCoCrNi was a single FCC solid solution alloy, while FeCoCrNiNb x was a duplex alloy with FCC phase and Laves phase. Only slight pitting occurred in FeCoCrNi and FeCoCrNiNb 0.15 , while 316 L had serious pitting pits. FeCoCrNiNb 0.15 had the best corrosion resistance. The passive film of FeCoCrNiNb 0.15 with the P-N junction had superior corrosion resistance than the FeCoCrNi passive film which mainly exhibited n-type semiconductor characteristics with less obvious p-type semiconductor characteristics. • FeCoCrNi is a single FCC, FeCoCrNiNb x is a duplex alloy with FCC and Laves phase • FeCoCrNiNb 0.15 shows best corrosion resistance, corrosion rate is one-third of 316L • Nb promotes the formation of P-N junction in passive film of FeCoCrNiNb 0.15